Secondary analysis will examine the risk of developing infections as function of various factors including time and load of carriage of resistant organisms and of exposure to antibiotics will be performed. Correlation with clinical isolates will be performed including typing, gene and plasmid analyses to determine correlation between colonising and infecting strains. Experiment simulating patient contact will be conducted to examine contamination of hands, gloves and gowns after contact in order to correlate between environmental contamination and contamination of healthcare workers. Additional work will be conducted on profiling bacterial communities by DNA fingerprinting techniques using length hetrogeneity (LH-PCR) and automated ribososmal internal spacer analysis (ARISA) on a sample of the patients studied.